the case of known, so-called bottom-feed, or side-feed injection valves, it is possible to measure the lift of a valve needle only through considerable expense, for instance, using a mechanical lift sensor, such as a measuring pin, given an installed restoring spring, against whose spring energy the injection valve is opened. In some cases, such a measurement is not even possible.
German Published Patent Application No. 40 23 828 describes a bottom-feed injection valve, in which the restoring spring does not have to be accessed to adjust the dynamic volumetric media flow. Rather, the restoring spring has a constant, preset spring energy. The dynamic volumetric media flow is adjusted by altering a magnetic restrictor constructed in the magnetic circuit. A magnetically conductive material, which alters the magnetic properties of an internal pole, is introduced into an internal pole of the injection valve to vary the magnetic force until the actual measured dynamic quantity (volume) delivered by the valve conforms with a specified, desired dynamic volume.
To adjust the static volumetric media flow during the open setting of the valve needle, it is necessary for the volumetric media flow sprayed off to be measured during a predetermined time and for the lift of the valve needle to be altered by shifting the valve seat member. A so-called "wet" adjusting method of this type is not only expensive, but also requires a later cleaning of the injection valve. It is not possible to directly measure the lift of the valve needle using known feelers because of the small diameter of the spray-off holes.